New Evolution
by bizarrebri
Summary: After the war Ichigo had disappeared. Four years later, with Grimmjow and Nell working with Soul Society, a group is sent on a mission to New York to investigate strange readings on reitsu detectors. What they find isn't what anyone expected, and could mean a new war.
1. Chapter 1

**Hello everyone. If you are reading 'What Was Once Lost' then this will probably seem very similar, but I promise you, they are different stories entirely.**

* * *

Four years have passed since the end of the Winter War and things have changed for the better, mostly. After scouting through Hueco Mundo, Urahara and Kurotsuchi hadn't discovered much, aside from a severely wounded Grimmjow and a small, crying Nelliel. They were both taken to the fourth division barracks for treatment, with Unohana attempting to restore Nelliel to her former glory whilst guards continuously posted in and outside of Grimmjow's room. It took about two weeks before the Arrancar finally woke up and was given the all clear. He was then taken to Shunsui Kyōraku; the newly instated head caption, after tragedy had befallen Yamamoto during the war. After interrogation, a long and tedious process due to Grimmjow's stubbornness, a captains meeting was held where they determined that Grimmjow was not a threat at present but would remaining under the watchful eyes of the Soul Society until further notice. Meanwhile, Unohana had discovered a way to repair Nelliel's mask, restoring her back to her adult form, although she still often acted and spoke very child-like.

After much arguing from Grimmjow and encouragement from Nelliel, Urahara took the two former Espada to his shōten in the world of the living, where they would spend their time maintaining the shop and helping with any stray hollows around Karakura town. Upon arrival, Grimmjow and Nelliel had demanded to see Ichigo, though both for very different reasons, but the former caption turned down the idea. He informed them that 'everyone's favorite substitute' was missing and had been for some time, the Soul Society being unable to find him, nor being able to narrow down the search to a specific world. This had upset Nelliel greatly, she even asked to see and speak to the teen's family, while Grimmjow simply sucked his teeth and mumbled about the orangette being pansy and running away. All the while, he was wondering where on earth the boy was and why he had a nagging feeling he should know, and be with him.

 **XXX**

In his four years of living with Urahara, Grimmjow had learned three things: Never, under any circumstances, say you're bored around Urahara, don't ever leave Nelliel and Yoruichi in the same room for too long, otherwise you will be the target of their evil games, and don't let Renji drink while Yumichika and Ikkaku are over.

Constantly being around shinigami wasn't as bad as Grimmjow would have imagined, especially when living with the eccentric group he did. In fact, he got along with Renji and Ikkaku rather well, the three always trying to find new ways to goad each other into fights. He'd also discovered a new found love for the sun. If he wasn't in the eleventh division's training grounds, it was common knowledge that Grimmjow could be found lounging around in a sunny part of Byakuya's koi garden or Ukitake's backyard. Over time, Grimmjow had also taken to spending the weekends with Kurosaki's little sisters.

The teen was still missing without a trace. Searches were still conducted, though infrequently due to the number of casualties during the war which resulted in the Soul Society needing all hands on deck, including ex-captain Isshin Kurosaki. Since he couldn't take his girls along with him to Soul Society, the Soul Society and the Kurosaki family came to an agreed upon arrangement. During the week, he would live in Karakura town but during the weekends, he would be required to go to the Soul Society. For a while they stayed by themselves on weekends, faring well for the most part, but one night someone broke into the house whilst they were asleep in their rooms. Luckily for the girls, Grimmjow had been out for a walk and passing by their house when it happened. The man picked the lock on their door, unaware of the glaring pair of blue eyes that watched his every move, and the moment he opened the door to enter; his face was smashed into the floor boards of the house, the loud yell and crash alerting the girls. After calling the police and sending a hell butterfly to Isshin, Grimmjow refused to leave the girls on their own. He took it upon himself to spend the weekends at the Kurosaki household, in order to guarantee their safety.

Over the past few months, the twelfth division had been getting some odd readings on the reiatsu detectors situated around the world of the living. Too many unknown reiatsu have been popping up out of nowhere, but when a team was sent to investigate, there was no trace of anything out of the ordinary. The Soul Society was on edge, fearing another on coming war, but Shunsui stayed on top of the matter whilst maintaining a sense of calm and order within the squads. However, today that would all change.

"Grimmjow, I want you to take Nelliel, Renji, Shinji, and Isshin with you on a mission in the world of the living. You will be heading to America to investigate another reiatsu anomaly. However, unlike before, I want you to stay for at least a month to investigate the area. If Urahara, Yoruichi or any of the Vizards wish to go with you, they may. I am already aware that Isshin will be taking his two girls along, seeing as school is out at the moment. We have managed to set up living arrangements for you already, though we have little in the way of human money to offer."

"I can take care of that, Shunsui!" Urahara spoke up in his usual giddy tone. "I have plenty of money saved up for situation such as this! Yoruichi and I will go with our brave little team, that way we can help in any way possible, and to observe a new culture, of course."

Grimmjow groaned. The 'observing a new culture' bit was sure to mean many nights of the pair coming back trashed beyond belief. He kept his mouth shut though, knowing that having the lunatic with him would probably end up making things go smoother anyways.

Shunsui laughed lightly at Urahara's enthusiasm. "That is all then. I would appreciate it if you could all go as soon as possible."

The group nodded and left to pack their things.

 **XXX**

It had been a few weeks and nothing even remotely interesting had happened, well aside from Urahara, Yoruichi, and Renji coming back trashed almost every night. It was amazing how many bars were in New York City. The group had fallen into a routine pretty quickly. Shinji and Kensei, who had come a long to ensure that Shinji kept himself in check, often stayed home to watch the house. Urahara, Yoruichi and Renji went out around dinner to get food and completely drunk, then they would come home, sleep it off until dinner the next day, and then repeat. Grimmjow, Nellie, Isshin, and the twins would go out each day to places the girls wished to visit.

The makeshift Kurosaki family had decided to visit a small park for the time being. The grass was a vibrant green and soft to the touch, there was a clear river flowing through the park with a small wooden bridge. The five of them lay on the grass looking up at the clouds when the strange reiatsu spread through the air and the river erupted. They all shot up immediately, Grimmjow and Isshin taking a fighting stance while Nell pulled the twins into a crouch beside her. As the river water fell from the sky, it turned into shards of ice, spearing dangerously into the lush grass below, causing Nel to cover the twins with her body as best she could. Soon the shards stopped falling, though not without scratching up Nel's back and the two men's arms and torsos. Across the lake, the group could see a woman dressed with long, black hair, wearing a fitted, short, ice blue dress with long sleeves. Her blood-colored eyes glared straight at Grimmjow.

"Really now, Siren? Do you really think us that dense, that you could just cut your hair and get yourself some new friends and we wouldn't recognize you? I know your little mother is around here somewhere with your whoring sisters and your insane uncle. They're probably hiding behind a tree crying in terror, aren't they? If you would just come with us, join us, we wouldn't have to go through all of this. You and your sisters have so much potential! You're being held back by your mother and the rest of that makeshift family of yours! You and your sisters could rule the new evolution! With our new abilities, we could rule the hollow realm, if you'd just help us! If not, then we'll have no other choice than to take over by force! If you're not with us then you're against us, and it will not end well for you or your sisters."

By the time she had finished speaking, the rest of the group from the Soul Society had shown up, pushing the twins stand behind them. Urahara, the most diplomatic of the group, stepped forward and spoke to the woman.

"I hate to say this, miss, but we have no one by the name of Siren here and none of us have seen you before. Though, would you care to explain to us what the new evolution is?"

"Really?" The woman raised an eyebrow at Grimmjow. "Your acting is pathetic, and quite cowardly."

Grimmjow was quickly becoming annoyed of this woman, who seemed to only be addressing him, and now calling him cowardly. This bitch was about to learn her place.

"Look, wench…"

"You know. I always knew you were a stupid bitch, but I didn't think you were this stupid. You can't even tell the difference between me and this guy, even though our spiritual pressure is completely different."

Everyone turned to the new voice, eyes going wide in shock. There stood another gigai of Grimmjow showing his signature, feral grin. However, the double looked a few years older with his hair grown out down his back. Even more surprising though, was that behind Grimmjow's double stood Ichigo Kurosaki, snickering along with an albino copy of himself.

* * *

 **A/N.** And that's the chapter, hope you enjoyed it. If you liked the chapter, feel free to leave a review/comment. Beta'd by Lady Histoire!


	2. Chapter 2

The group from Soul Society stared long and hard at Ichigo, though Ichigo and his albino copy seemed to ignore them in favor of the woman across the lake.

"We've been through this before, Sienna. You cannot have Las Noches! We will fight until our last breath to ensure it stays out of your hands. You say that my family and I are weak, though when's the last time you won a fight? Last time, I wiped your ass across the throne room without even unsheathing my sword."

The venom in his voice and the spitefulness of his words was something that shocked his old friends.

"Unless you want to lose half of your pathetic army right here and now, I suggest you leave for another day, because I could tear you to shreds without even having to think about it", uttered the albino copy with an eerie voice.

The woman, Sienna, stood for a moment, trying to think of some way to finish the argument in her favor, but found nothing. Instead, she huffed angrily and promised that she would be back with an army too powerful to resist before turning ice and shattered into thin air.

Afterwards, Grimmjow shot forward towards Ichigo, grabbing him by hair and lifting him off the ground. The orangette clawed at Grimmjow's wrist and kicked the air in attempts to escape.

"I want an explanation, now!"

The teen didn't answer nor glance at Grimmjow, too busy trying to get free. Moments later, Grimmjow felt a jolt of electricity shoot up his arm, causing him to hiss and drop the teen into the arms of the younger counterpart.

"Don't. Ever. Touch him again!"

The complete and utter hatred that seethed through the boy's words were shocking to everyone. How could he seem to have so much hatred for someone he'd never met? Isshin and the twins made their way towards Ichigo, who was rubbing his scalp with a scowl on his face. Isshin's voice was shaky as he spoke to his only son for the first time in four years.

"Son, where have you been?"

Ichigo stared at his father with a deep scowl, before briefly looking behind Isshin to observe everyone else.

"Ichi-nii, are you mad at us? Did Karin and I do something wrong? Please tell us. You've always been so bad at sharing your feelings with people Ichi-nii. Please tell us, we can't make things better if we don't know what's wrong. You...you h-have to…"

Yuzu tried to finish her ramblings but was unable to due to her own tears. In the end, she simply bowed her head into her hands. Ichigo's scowl softened into one of sorrow as he leaned forward and gathered her into his arms, rocking her gently, all too used to comforting crying children. Eventually, Ichigo carefully stood whilst holding Yuzu, nodding his head to everyone to follow him.

 **XXX**

After a twenty minute walk, the small crowd arrived in front of what most humans would consider a mansion, though Ichigo had come to simply call it his home. The orangette opened the unlocked door and walked inside, telling Siren to lead their guests to the meeting room while he took a sleeping Yuzu upstairs to rest.

The meeting room was a large room with dark great walls and a soft, black carpet. Inside were many low rise tables surrounded by dark grey bean bags and a colourful collection of pillows. Siren and Ichigo's copy, who had yet to identify himself, threw themselves down on to the piles of pillows while the group from Soul Society sat collected in one corner. Moments later, Ichigo walked in, wearing black sweatpants with a matching long sleeved top, and plopped down on a large bean bag between the other two men.

"Well, I don't really know where to start this..."

He stated awkwardly. Siren moved to lay his head in Ichigo's lap, the smaller male smiling whilst threading his fingers through long blue locks.

"Well, Kurosaki-kun, you could start by why you disappeared after the war." Urahara stated calmly.

"In order to do that, I'd have to be one hundred percent sure you won't go running to rat me out to old man Yama. I ran because of him and I'll be damned if I end up in his hands now."

"Well, seeing as Yamamoto is dead and Shunsui is our new head captain, you really don't have to worry about that."

Ichigo tensed and fell silent for a few moments, as the information sank in, he nodded his head.

"I see. Well, I guess Shunsui has always been less willing to execute people, and it's not like he could get his hands on all of us, even if he tried. So, I'll tell you my side of the story…"

"Ah, ah, ah! Not so fast, King. If they wanna know what the 'ell we been through, I got a condition for 'em."

After sharing glances, Urahara nodded at the copy's request.

"What may this condition be?"

"I want to know why Grimmjow left a pregnant beta. HIS pregnant beta."

Nelliel gasped loudly, others looking at Grimmjow in disbelief. The shinigami had learned about hollow mating rituals long ago from both the vizards and the ex-espada, so they knew that leaving a pregnant beta alone, as an alpha, even if it wasn't yours, was frowned upon, but leaving your own beta alone during pregnancy, you could and most likely would be killed for the act.

"What the hell are you on about, snowflake? I've never marked a beta and I sure as hell ain't gotten one pregnant."

"Oh really now? Then can you fucking explain…!"

"Shiro, you're upsetting ma."

At Siren's comment, Shiro turned to look at Ichigo, whose eyes were downcast. The albino let out a regretful sigh, quieting down so that his king to tell their story.

"I'm not really sure how much of the war I missed after I defeated Aizen. I know there was still some fighting going on but I don't know how long it lasted. After my fight with Aizen, I fell unconscious and didn't wake up for several hours. When I did wake up, I was buried under a mound of rubble. In my condition, I couldn't possibly dig myself out on my own, so I was forced to lay there waiting. I couldn't even yell for help, my voice was little more than a whisper. Shiro is my inner hollow, though he only resided inside my inner world at the time, but I couldn't even call on him for help, so I was completely alone. Eventually, I heard voices and I thought some shinigami had finally discovered where I was, but instead of shinigami I was greeted by Nnoitra and Ulquiorra."

Ichigo heard soft gasps. When he looked up, he saw a mixture of shock and confusion on the faces before him, though he was thankful that they seemed intent on letting him finish without any interruptions.

"Nnoitra wanted to kill me immediately though Ulquiorra wanted to take me back and see if I had any useful information. They argued for a while until Ulquiorra studied my spiritual pressure more closely; it wasn't just mine, I had four extra spiritual pressures mixed in with mine, though at the time they were very weak. When he realised this, Ulquiorra began tearing at the rubble so fast I could barely see him moving. Nnoitra joined in after he realized what Ulquiorra had. They carried me back to Los Noches were I found out that a several of the espada had survived, along with Aizen and Gin."

The entire room tensed and Ichigo gave a soft smile as he nodded his head.

"I know, I know. I had the same reaction. His death had just been another illusion. After the battle, he gathered all the espada he could find and did his best to heal them, which obviously worked. I tried to escape, to tell Soul Society, but I was too weak and there were too many of them. They tried ascertaining the identity of my alpha, but in all honestly, I had no answer for them. I was still trying to process what they had told me; that as a seventeen year old boy, I was pregnant with four children. After a few weeks, I was back to an acceptable health and I could finally talk to Shiro again. He told me that the reason I had been unable to talk to him was because he'd sealed off all his energy in order to keep the children safe. He also told me who my alpha was and that I couldn't access my memories of the encounter because he had sealed those off too. It took me a week to convince him to unseal them, and when he did, I could see for myself that it was true. They put me in Grimmjow's old room, though I spent more time sleeping with Starrk in his mountain of pillows. After a few months, I started to show and it was hard for me to move around freely, so I was forced into bed rest by Szayel and the other betas while everyone took turns taking care of me. Until then I hadn't actually seen Aizen, but one day he was the one that came in to take care of me. After my initial reaction of attempting to flee, we talked for almost the whole day. He explained to me that he no longer had any intention to harm Soul Society or the world of the living. He just wanted to live peacefully in Hueco Mundo with his arrancar and espada. I asked him why he hadn't fixed Grimmjow, but he told me that you were fine, and you'd joined the Soul Society along with Nell. Szayel said that you'd come looking for your beta, that you were one of the best alphas he knew. Ulquiorra and Nnoitra expressed explicit hatred for an alpha that'd leave 'such a strong beta' all on their own. Harribel and Starrk were the only neutral ones, of course. Herribel simply told me, that what would happen was what was to be. That if you came back then I would have an alpha and a family. However, if you abandoned me, I was still a strong beta that could make my own family, and that no matter what, I'd have the support of Las Noches. It took about five months for me to finally give up hope of you coming for me and around that time Shiro started to materialize outside if my inner world."

"I fuckin' had to! I was drowin' in there because you were so depressed that your shit excuse for an alpha left you!"

Ichigo shook his head before continuing.

"The rest of my pregnancy went by with ease and soon I was in labour. The first born was Siren; he got his name from the Greek myths about sirens leading sailors to their deaths by appearing to them as their desires. As you can see, Siren is the exact copy of his father, right down to the jawbone, eye markings, and hollow hole. Second was Auryon; her name means 'great huntress', I knew from the moment I laid eyes on her that she would be one. She has stormy blue hair and bright blue eyes with pointed ears, a tail, and a crown of bone, just like Grimmjow's resurrección. Third was Zilli: her name means 'my shadow', as she looked exactly as you'd imagine Shiro to look as a baby; paper white skin and hair, and the eyes of a demon. My last daughter was so tiny that Szayel didn't think she'd make it, but I knew she could. When I had my first look at her I could barely stand it, with her little tuft of orange hair and her wide blue eyes, her nature so calm yet curious, I had to name her Misaki. If I had named her anything else it would have felt like a betrayal to her."

The room was filled with Isshin's sharp and shaky intake of breath.

"Can... can I meet her?"

"Uh, yeah… when she comes home. I don't really know where she is right now."

Shinji raised an eyebrow at that statement, stating his confusion.

"Wait, you don't know where she is? Shouldn't she only be around four years old?"

"Do I look four years old to you, Blondie?"

Siren sounded highly offended at the thought of being mistaken for a small child, making Ichigo laugh.

"By human age, yes, but hollow children age much faster, due to the amount of spiritual pressure around them. They aged about four times faster than a normal human child would, so they are around sixteen years old, though Siren refuses to settle for anything under seventeen."

"I'm the oldest dammit!"

"But not the brightest", came a woman's sing song voice, everyone turning to watch a tall woman with an ample body walk in with a grin plastered on her face.

"Aury, must you tease your brother? We just fixed the outside wall after your last fight."

"But ma, he makes it so easy."

Siren growled as he shot up to standing nose to nose with his sister. He glared down at her whilst she smirked back at him with narrowed eyes. Ichigo sighed, not wanting a fight to break out right now.

"We have guests, you know."

Auryon hmphed as they both backed away from each other, before turning to look at their guests. When her eyes landed on Grimmjow; she hummed before walked towards him, crouching, inches from his face. Before Grimmjow could defend himself, she slam her hands against both of his cheeks, smooshing his face and triggering a headache.

"Ah, bitch! What the fuck was that for!?"

"Really? You're a dick, now I know where Siren gets it from."

"Hey!"

The two yelled in unison, everyone else in the room shaking their heads.

"Well, now King's told his part, so it's your turn, pussycat."

"I think I'd rather discuss that with Ichigo, alone."

"Like hell-!"

"Shiro, its fine. I can deal with this myself. Aury, Siren, why don't you show everyone around the house. Shiro, go out and do something productive."

Ichigo stood, leaving no room for argument. As he walked towards the doorway, he waved his hand, motioning for Grimmjow to follow after him.

 **XXX**

 **A/N.** And that's the chapter, hope you enjoyed it. It ended up being longer than I'd planned. Sorry about that. I had to explain what had happened to Ichigo and I'm not a fan of writing flashbacks. With that explained, there will be more action.

If you liked the chapter, feel free to leave a review/comment. Beta'd by Lady Histoire!


	3. Chapter 3

It took the group about two hours to see the whole house, due its six stories. The first floor was what you'd expect in every house; kitchen, which was as big as one in a high class restaurant, dining room, equally as big, two living rooms, and a few bathrooms. Beyond that, Ichigo and his family shared the second floor, Nnoitra and Ulquiorra were on the third, Gin and Aizen the fourth, Starrk and Harribel the fifth, and Szayel was on the top floor. Each floor housed rooms fitted to the people living there, such as sparing rooms, computer labs, and gaming rooms.

It all seemed beyond affordable unless Aizen had taken up bank robbery as his new hobby. Upon asking what everyone did for jobs, Isshin could understand why this level of living was attainable. It seemed that Aizen had somehow managed to open an extremely successful business, known by the high ups in many countries across the world. For the most part, it was a bounty hunting agency that went after large time crime bosses and gang leaders that the police couldn't catch, though they did do local 'Is my husband cheating on me?' and 'My angsty teen ran away' cases every now and then just for shits and giggles. Starrk and Harribel were head of personal, arranging appointments and meeting with clients. Aizen and Misaki handled finances. Nnoitra worked as the hacker of the team; he could hack anything from a facebook account to secured government documents. Ulquiorra and Shiro were the assassins for when a particular job required someone dead. If it was a 'search and retrieve' mission, Auryon and Siren were the ones for the job, though the job had almost as much blood shed as any assassination assignment. Zilli and Gin functioned as the spies of the operation for missions. Szayel was in charge of weapons and tech, constantly making sure weapons, poisons, and technology were functioning at full capacity and as efficient as possible. Ichigo didn't exactly have a title; he would simply do whatever job interested him most at the time and no one seemed to have a problem with it.

After the tour and explanation of their business, the group ended up in the main living room. They weren't there for long, as a serious of crashes and curses soon erupted from the front door. Auryon and Siren spoke in unison.

"Nnoitra and Zilli are home."

"Your mother named you right! Fucking 'my shadow', you might as well be up my ass, wanna get any closer, ghosty!?"

"Oh shut your mouth! It's impossible not to be in your shadow because you're the size of a fucking bean pole, dick head!"

"Oh shut it, you wretched piece of -"

"Now, that wouldn't be Nnoitra that I hear degrading my daughter, now would it?"

All voices went silent when Ichigo's tone spread through the first level of the house. He wasn't angry, but his tone dripped with playful malice that could sometimes end up being as bad, or worse, than anger.

"Of course not, Ichi. Never. I love lil Zilli with all mah heart."

Siren and Auryon snorted as they stood and walked towards the entryway where they knew the other three would be; not really paying attention or caring that all the others were following. Nnoitra stood with a large grin on his face and his arm draped, a little too tightly, around Zilli's shoulders. Ichigo stood halfway up the staircase, showing the tell-tale signs of his current mood. Normally Nnoitra would just leave it alone because on occasion Ichigo would fall into a slight depression and no one mentioned it because that's the way he preferred it; though they still all hovered over him to make sure he was ok in their own way, and that was how Nnoitra planned on treating it this time. Though that changed when he saw who walked down the stairs after Ichigo. His arm slowly unwrapped from Zilli and moved down to her arm to put her behind him as he took a few steps forward.

"You rat bastard, son of a bitch. Where the fuck have you been, huh? Found something better and chased after? Decide you didn't want a family? What in the hell-"

"Nnoitra. Not now. Where's Misaki?"

Nnoitra bit his lip to keep quiet for a moment before sighing.

"She's with Aizen, they should be home soon."

 **XXX**

After their visitors had returned to their own residence, Nnoitra, Ulquiorra, Aizen and Shiro with Ichigo on his lap, sat at the bar located on the third level to discuss Ichigo and Grimmjow's earlier conversation.

"Most of it was just him asking questions. How, when, where, the basic stuff. He says he doesn't remember a thing, tried to blame it on Aizen's illusions."

"Impossible, the second I took down my illusions, which they all are, he would have remembered."

"I know, and that's what I told him. He said he'd talk to Urahara about it. He said he'd always felt something, like a 'pull' or something, but thought he just wanted to fight me."

Shiro merely mumbled 'shit head', whilst Ulquiorra sighed his favorite insult, 'trash'.

"He told me he wants to know the kids, he never really wanted any or a beta even, but now that he has them, he might as well take care of them."

Nnoitra scoffed. "So now he just wants to waltz up in here, take you as his beta, take his kids and what? Bring you back to those shit head shinigami that would've left you for dead?"

"I-I don't know. I still...I still want him, I don't know if it's because he marked me back then or if those are just my feelings but I want him to be there, with me and the kids. But I can't go back there. I won't."

"Well then, that's what you need to find out. If it is what you choose, he may stay here with us. You are well aware you are family too me, and as are your children. Anything you wish, I will do my best to make true."

Ichigo nodded at Aizen's words, knowing the truth behind them. Though Aizen seemed cold hearted and cruel, he truly did care and would protect what remained of his family of espada at all costs.

...

 **A/N.** If you liked the chapter, feel free to leave a review/comment. Beta'd by Lady Histoire!


End file.
